The present invention relates to differential amplifiers, and in particular to circuits for providing a common-mode feedback to such an amplifier.
Differential amplifiers typically have an output common-mode level desired signal provided to them. The common-mode feedback will adjust the output common-mode level in the amplifier to match the common-mode desired level through negative feedback. It is desirable to set a common-mode output level that gives the largest differential output swing possible.
Typically, a common-mode desired voltage signal is generated globally and distributed to individual amplifiers. A typical method of generating such a signal is to use a resistor divider between the positive voltage supply and negative voltage supply. This signal is then provided to the individual amplifiers as the desired common-mode signal.